Piston



Oct. 2, 1928.

E. M. WILLIAMS PISTON Filed Oct. 27, 1921 intended for use in thecylinders oi internal- Patent'ed Get. 2, i928.

barren res:

1 v EDWARD wILLIAMsoF ELYRIA, "0310.

rrs'ron.

- Application filed. October 27, 1921. Serial No; 510,866.

. Thepresent invention relates to a piston for-use in cylinders and ismore particularly combustion engines. I

piston in and this is usually taken care or by mach1n-- p Experiment hasdemonstrated that when a piston or usual construct-ion such as a castiron piston is in actual operation in a cylinder of an internalcombustion engine, the temperature at the top end or head'of the pistonis greatest and decreasestoward the inner end or skirt of the cylinderwhere the tem perature is the lowest. This will be evident because thehead of the piston is exposed di rectly to the heat incident to therepeated explosions I ing an integralbody, the heat which is imparted tothe head of the piston is in part 7 transferred to the body of thepiston in accordance with the laws of the conduction 0fing a pistonso'thatit is ofslightlytapering form. The difficulties and disadvantageswhich are incident to the usual typeo'l' cast iron pi'stons and theleakage'oi' oil around the pistonsinto the combustion chamber of'theengine or conversely the leaking ofgasolme past a piston lnto thecrankcase, and ,addi

tionally, the excessive weight 0]: cast iron pistons andthe disadvantageo'fmoving the large mass 01 iron, are alltoo' well known to requirecomment. a

It is the purpose ofthis' inventlon'to provide apiston which is (soconstructedthat by far the greater portion'of the heat which is impartedto the piston incident to its operation is retained in the head portionof the pis? ton and only a small fraction of that heat is transmitted tothe central portion of thebody of thepiston; and to the skirt. of the"piston. Additionally, provision is also made so that heat which may.be'transmitted to the body of the piston is only transmitted indiminishing degreeto the skirt portion of the piston.

This construction enables a piston tojbe I of the fuel mixture. Thepiston be fitted much closer within the walls a .cylind'er and thisresults directly in. eliminating the usual sloppy fit of a pistonand onthe other hand enables that the skirt'portion-of. the pistonparticularly, may beifitted rather exactly and have a much closerworkingiit a 7 within thewalls or the cylinder than can possibly beattainedwiththe types ofpistons, with which Iain familiar.

The cylinder also provides a construction wherein the compressionringsmay be as.-;

sembledi on the piston without the necessity of removingtho pistonfifromthe cylinder in which'lt may be placed.

" Reference should behad to theacconipanying drawings. forming apart ofthis specificationin which Fig. 1 is .a sectiona-leleva tiono'f a pistonembodying my invention; Flg. 2 is atop plan view on reduced scale;

Fig. 8 is a plan view showing the compression rings and thetension.memberwhichpushes themoutwardly.

-Referring to the drawings, 11 indicates what may be termed the body ofthepiston.

anditis provided with the inwardly extend-f ed'sl'eeves such asindicated at 2ttor theres I so ception of a wrist pinfthe same as inusual ractlce' The upper end of the body lis provided withan externalwIGCQSS-JOI groove 1 which is indicated'at 3, this groove beingindicated for the reception of; the compression ring as will be laterdescribed;

' At thecentral portion atthetop ofthe I body portion 1 there is abossziin to which is threaded the member which holdslthe head of the pistonin its attached relationship to j the body portion: as well be laterdescribed.

Atthe lower or inner end of thebody po tion there ispalso'aninwarclly,"extencling p I groove or recess'as indicated at 5, thisgroove or recess being for the-reeeption'oi' the usual oilrings/f' p Thebodyporti0n1'is made hollow according'to usu'al practice. I I Thehead'o'f the piston is indicated at 6 andit is provided wit-ha centralretaining screw 7 1 which is threaded into a suitable opening in theboss 4 thus serving as aretaining means'for the head; i ihereare {alsoas indicated at 8 which prevent relative turning between thebody of thepiston 1 andth'e head member 6.

' provi'ded'one ormore auxiliary screws such These "various threaded pmembers are made to have only a fairly close fit sonthat when the headof the piston bestated.

provide a gasket 9 which is made ofany suit,

able composition or material which is efficient from the standpoint ofthe non-conduction of heat. Asbestos is a material from which such agasket maybe made. This gasket is retained between thetop of the bodyportion 1 and the-underside of the'head when the head is secured on theb. dy portion as before The skirtmember of the piston is made as aseparate element and SECUI'Lhl to the body of,

the piston at the lower or open side thereof. In the present instancethis is accomplished by providing the lower portion of the body 1 withan inwardly extending shoulder 1 which is threaded upon its interiorsurface. The skirt'member'proper which is represented at 10 has at oneend a shoulder 10 and an upstanding neck 10", which on its outer surfaceis threaded and may be attached to the lower portion of the piston body1 by the screw thread engagement which is suggested. This particularmethod of securing the two parts together is but suggestive ofanydesired method. The width of the shoulder 10 is such thatwhenassembling with the body 1- the outer surface of the body 6 issubstan-.

tiallyin the same cylindrical plane as the outer surface of the bodyjlof the piston.

It will thus be seen that the pistons-which has beendescribed is made upof three parts which may be described as, the head, the bodyv portionand'the skirt portion- The head is preferably made of a metal which hasa low oo-efficient of expansion and one which is nonwarping under theaction of the-high heat to which it is subjected when'in use. The

Iniddle'section or body portion of the piston is preferably made ofamuch lighter metal 1 than the other portions and for this purposealuminum or aluminum alloy has been found to be suitable. The lower orskirt portion of the piston is made of a material having a lowco-efiicient of expansion, which metal at the same time has theproperties of resistant to V wear.

The head member. 6 is made of such a diameterw'ith respect to a givencylinder into which it isto befitted so that when within thecylinder and'under'workingconditions,

the expansion ofthe head under the tempera" tures to which it issubjected to in use, will cause suiiicient expansion so that the headportion will'have a nice working fit within the cylinder. The centralpart or body portion ofthe piston being made of material of low specificgravity will materially reduce the weight of the combined portions ofthe piston so that V the total weight of the three portions may be lessthan the weight of the usualcast iron piston of light dimensions. Thebody portion is made of such diameter with respect to a given cylinderinto which it is tobe used, so that under expansion the body portion ofin the cylinder.

the piston will have, anice working fit with The skirt portion is madetohaveadianieter, and clearance with respect to a given cylinder so thatwhen in use and expanded by such heat'as it. receives, it will have anice" working fit against the wall of the piston.

WVhen such a piston as has been described is used, in an internalcombustion engine, the

first application of heat incident to the running of the engine comesupon the head ofthe piston and very quickly the head of the pistonexpands to'its ultimate amount.

Tlhe conduction of heat from the head to;

the body portion is materially reduced due to the provision of the heatinsulating means betweenthe body portion and the head so that the bodyportion of the cylinder can never be come ashighly heated as would bethe case if the body portion and head of the piston were integral. Fromthe foregoing it will be readily deducedthat the heat which theskirtfportion of the piston receives, is Very much less than would bethecase were thepiston made as an integral structure and, experiment has 1demonstrated as a fact that the transfer of;

heat from the head offthe piston to the skirt portion is so reduced overwhat would be the case in a solid plston, that the temperature which isattained by the skirt portion will never be so hlgh as to affect thelubricat ng qualities of' the oil used in crankcase lubri; cation,whereas with the solid types of pistons.

now in use the breakingdown of the lubricatmg oil in the crank case anddestroying its lubricating properties is the usual occi'irren'ce unlessa very good grade of oil be used, which isof course relativelyexpensive. 7 By making the piston inthe three parts as above suggested,the head maybe constructed so that} it will expand in accordance withthe heat which it receives and when soheated, provide a nice fit withinthe cylinder, also the body. portion may be so made andlmachined that itwillwhen expanded the heat which it receives, have a good workingfit inthe cylinder, and the same is true with respect 'to the skirt portion.Therefore with each of these partsflof the piston being particularlyconstructed so as to take care of the temperatures to which they areindividually subjected and at the same time provide a nice fit in thehind them, thus constantly urging the ring cylinder when in heatedcondition, insures that the piston under worklng conditions will at allportions of itsengagement with the walls of the cylinder have a properfit and not a loose or sloppy-fit, and thereby the passage of oil beyondthe piston into the combustion chamber is minimized.-

Due to the fact that the skirt portion 10 may be so nicely fitted withinthe cylinder due to the construction of the piston as before explained,the skirt portion of the piston will always be in bearing relationshipwith the wall of the cylinder and so serve as a sort of a' cross-head,and eliminate any other movement of the piston than a true reciprocatingmovement.

In the groove or recess?) there is in Fig. 3 and comprises the threesections which areindicated at 11, 11 and 11 The ends of each of thesesections are provided with notched extensions such as indicated at- 12,which extensions overlap'and engaging each other in the manner shown inFig. 3.

When these sections are inserted in the groove or recess 3 a springmember 13 is placed besections outwardly and against thewall of thecylinder. Attention'is called to the fact that by-the ring constructionwhich has been shown the piston has been in use and it is desired toplace a new compression ring in thersame, the compression ring may beplaced, w thout removing the piston from the cylinder.

This may be accomplished by removing the head of the engine andreciprocating the piston until the head of the piston is at the top ofits stroke. The head 6 may, then be removed, thus exposing the groove 3and permitting the removal or placement ofthe seg' ments of thecompressionring.

When a new compression ring is placed in a piston it is possible to usea rather stiff spring behind the segments of the ring, and by this Imean a spring which is much stifier than would be necessary in theactual operation of the piston. This will cause the segments of the ringto exert a rather heavy outward pressure against the inner wall of thecylinder.

The head may then be placed and the engine mechanically turned over fora desired period of time, thereby wearing in the ringsl After thiswearing action has been permitted for a I located the compression ringwhich is shown in plan vlew in the under side of a ring segment.

sufiicient length of time, the head of the piston i may be removed; anda lighter springsubstie.

tu-ted 'forthe heavy spring which hadhereto: I

fore been used behind the compression ring. Then the'head of the pistonmay be replaced and t'he head of the ring assembled on'th'e blockthereof.

By the procedure whichhas just been out I lined it isposs ble to givetherings a pier; liminarywearing in, which in the usual types of piston canonly be accomplished by actually wearing the rings inby use. ThisWearing in action makes the engine Jvery still and all this may be to alarge extent obvi:

ated with the type of piston herein proposed in the manner which hasjust been described.

In the groove or recess 5 is positioned the oil ringas indicated at 14.This oil ring is constructed with segments the same as explained withrespect to the compression ring and the segments of the oil ring arepushed outwardly by means of a spring 15 in pre cisely the same manneras has before been described. 1

lflach of the segments of the oil ring and the compression ring areretained against undue radial movement by means of pins, one

of which is 'indicated at 16 in Fig. 1, one end 7 I of the pin beingsecured with a driving fit in an opening in the body member 1, whlle theother end of the pin extends into a slot I such as indicated at 17,which slot is formed slot is slightly elliptical in shape so as topermit a limited'radial movement of the ring sections.

Having described my invention, I claim:-

The I V 1. A piston comprising a body: portion,

head portion, which head .pOrtion is 'separate from but secured to thebody portlon,

heat insulating means interposed between the head and body. portion'anda skirt portion associated with thebody portion which is made separatefrom but attached to the lower part of the body port-ion, thesaid headpor-' tion and the said "skirt portion beingmade of metalwhich has a lowco-elfic ent of-ex-,

pansion as-compared to that of the bod-y I portion. I v V,

2. A piston provided with a rln'g groove, aring in said'groove, saidring comprlsmg a plurality oflsimilar segments wlth overlapping endjoints, a spring belnnd sald-seg ments and-urging them outwardly, andpins carried by the piston and engaging anedge of each of said segmentsat the center thereof to limit the radial movement of the segments 3. Apiston having a body portion, a head which ismade distinct therefrom andate 125 tached thereto and a skirtportion which is made separate fromthe body portion and attached to the lower endv of the body portion,said head and skirt being made of metal having a lowco-efficient ofexpansion and said body portion being made of a metal .130

Which is. materially lighter than themet al of the head and skirt.

4. A piston havinga hollow body portion provided With means forattachment to a connecting rod, a head separate from said body portionand-attached thereto, heat inof, said head and skirt being made of metal10 i having a low CO-GffiC-lGIlt of expansiomfand I said body portion;being made of a. metal which is materially lighter than the metal ofthehead and skirt.

y In testimony whereof, I hereunto afiix 15 signature.

E WARD W LLIA S. 7

